Results from our previous studies support an hypothesis that hypertension in older humans is related, in part, to an age-related increase in SNS activity coupled with diminished ability to normally down-regulate a-adrenergic responsiveness. The general hypothesis which will be tested in the studies described in this proposal is that in older hypertensive humans with increased SNS activity and metabolic insulin resistance, there is also resistance to insulin's vasomotor effects which interferes with down-regulation of a-adrenergic responsiveness.